Recently, electronic devices such as a computer and a network device use a plurality of devices to improve the processing capacity thereof. A method of operating the plurality of devices in parallel to perform distributed information processing or distributed arithmetic operation is mainstream. Since there is a limitation in floor area for installing the electronic device, a method of mounting a plurality of electronic devices on some racks collectively has been adopted. In order to mount as many as possible electronic devices on the rack, the height of each electronic device needs to be lowered. Consequently, a tall heat sink cannot be mounted immediately above the LSI or IC. Therefore a method is adopted where heat is transferred to a place away from the LSI or IC by using a heat pipe or the like, to dissipate heat to the atmosphere by a fin or the like provided in a condensing section at the end of the heat pipe at the destination.
However, when the electronic device represented by a 1 U server or a blade server is a low type device having a height of about 40 mm or less, an area ratio of a hoard for connecting between respective devices, referred to as a backplane and a middle plane for performing signal transmission or power feeding, which is provided in a direction of wind of the device, becomes relatively large. Therefore, an opening for sending cool wind into the device, a so-called air hole, is only minimally provided in the electronic device. Consequently, wind is forcibly fed by a fan having high static pressure in order to circulate wind to a small opening, and hence the driving power and noise of the fan increases more than necessary.
Therefore, a method of conveying heat to the outside of the electronic device and intensively cooling a radiator provided at the destination has been devised. In FIG. 8 of Patent Document 1, although not a device unit, there is disclosed a structure for conveying heat generated by each card to a condensing section provided above the card, and connecting to a cold water pipe arranged beforehand in a casing to dissipate the heat. In FIG. 4 of Patent Document 2, there is disclosed a structure that uses a heat pipe and is capable of connecting and disconnecting between a condensing section thereof and a heat sink serving as a radiator.